<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
			html, body{
				height: 100%;
				overflow: hidden;
			}
			#canvas{
				position: absolute;
				left: 0;
				right: 0;
				top: 0;
				bottom: 0;
				margin: auto;
				background: gray;
				
			}
		</style>
		<script>
			// 同步思维, 有别于浏览器本身的渲染机制
			window.onload = function(){
				// 拿到画布
				var canvas = document.getElementById("canvas");
				
				if(canvas.getContext){
					var ctx = canvas.getContext("2d")
					
					ctx.rect(50,50,100,100)
					
					//ctx.fill()
					ctx.stroke()
				}
			}
		</script>
	</head>
	<body>
		<canvas id="canvas" width="600px" height="600px">
			<span><a href="39.108.121.57:8080">您的浏览器不支持画布元素, 请您换成萌萌的chrome浏览器</a></span>
		</canvas>
	</body>
</html>
